Electrical cogeneration system and method

ABSTRACT

An electrical cogeneration system and AC coupling method for efficiently distributing power from multiple AC sources. The system includes a main AC source, an AC generator, a solar panel, and an automatic transfer switch. The main AC source and the AC generator are connected to the transfer switch. The system also includes a DC/AC inverter, which is in communication with the solar panel. The transfer switch and the inverter are both connected to a common AC load panel where the power provided by the solar panel, the AC generator, and the main AC source is used to satisfy a common electrical load. The system further includes a system control device that is in communication with the inverter and the transfer switch and is capable of selectively determining power input to the AC load panel. An AC coupling method for distributing power from multiple AC sources is also provided.

FIELD OF THE INVENTION

The invention herein pertains to electric cogeneration systems generallyand particularly pertains to a system and method for efficientlymanaging and distributing power from multiple AC sources.

DESCRIPTION OF THE PRIOR ART AND OBJECTIVES OF THE INVENTION

Electric cogeneration systems have progressed from expensive industrialexperiments to applications in commercial, residential, hospital, andenvironmental spheres. Early cogeneration systems relied on internalcombustion engines, coal-fired generators, and hydroelectric turbines asmechanical power plants to supplement electrical power available fromutility companies. Later, solar panels, wind turbines, and tidalgenerators were also incorporated into electric cogeneration systems.These environmentally friendly methods of producing electricity are alsocheaper to operate because they focus on harvesting naturally occurringpower sources instead of producing the energy with fossil fuels.However, the laws of nature prevent these environmentally friendlymethods of electrical production from functioning at all times.Therefore, it becomes necessary to monitor an electric cogenerationsystem for fluxes and losses of electrical power when a system is underload.

Conventionally, it has also been necessary to include heavy, expensive,and toxic DC battery banks to store electrical energy for circumstanceswhen sun generated electricity is unavailable or the AC utilityelectricity required by the common AC load is also unavailable orinsufficient to meet a given need. A storm causing loss of AC utilityelectricity and solar generated electricity is a common example. Underthese circumstances, current cogeneration system design and productavailability mandates the use of large, multiple DC mass electricalstorage devices (conventional lead/acid DC battery banks for example) toprovide DC electrical energy to allow a solar DC/AC inverter to producerequired AC voltage, frequency, and amperage (commonly called AC power)to meet the common AC load requirements. DC battery banks coupled tosolar AC Inverter output is extremely inefficient, as up to 40% of theenergy conversion lost to heat in the components and conductors.

Several existing DC systems exist for the collection and distribution ofDC power. Many of these systems focus on direct current (DC) storagebecause the flow of electrons are in a constant direction, compared toalternating current (AC) which periodically reverses direction. SeveralDC to DC coupling systems exist for the collection and distribution ofsolar derived DC energy for example U.S. Pat. No. 7,696,642. This systemcollects all DC derived energy into a DC battery bank, DC load issupplied directly from DC battery bank(s), produces AC power provided bya DC/AC inverter that is always supplied by the DC battery bank.Therefore, it is desirable to create an electric cogeneration systemthat operates with AC, as opposed to DC voltage.

The use of an AC generator is always used as either an AC/DC batterycharger or to supply the AC common load directly, bypassing the solarDC/AC inverter. AC coupling is not utilized in this design or anypreviously existing system, patented or otherwise. It is therefore ofgreat social and economic importance to design a solar AC inverter tosynchronous AC generator direct AC coupling system to eliminate theoperational inefficiencies inherent to U.S. Pat. No. 7,696,642 andsimilar systems, and provide life essential and sustaining AC powerunder all circumstances regardless of the availability or usability ofAC utility to the installation.

As referred to herein, the term “system control device” should bebroadly construed. It can include any type of device capable ofpresenting electronic data to a user. For example, a system controldevice may be a computer configured to present AC current data to auser. Examples of such computer include, but are not limited to,conventional desktop computers as well as laptop computers. In anotherexample, a system control device may be a mobile device such as, forexample, but not limited to, a smart phone, a cell phone, a pager, apersonal digital assistant (PDA), a mobile computer with a smart phoneclient, or the like. A system control device may also be a typicalmobile device with a wireless data access-enabled device (e.g., aniPHONE® smart phone, a BLACKBERRY® smart phone, a NEXUS ONE™ smartphone, an iPAD® device, or the like) that is capable of sending andreceiving data in a wireless manner using protocols like the InternetProtocol, or IP, and the wireless application protocol, WAP, orBLUETOOTH® in addition to serial communication protocols such as MODBUS.This allows users to access information via wireless devices, such assmart phones, mobile phones, pagers, two-way radios, communicators, andthe like. Wireless data access is supported by many wireless networks,including, but not limited to, CDPD, CDMA, GSM, PDC, PHS, TDMA, FLEX,ReFLEX, iDEN, TETRA, DECT, DataTAC, Mobitex, EDGE and other 2G, 3G, 4Gand LTE technologies, and it operates with many handheld deviceoperating systems, such as PalmOS, EPOC, Windows CE, FLEXOS, OS/9,JavaOS, iOS and Android. Typically, these devices use graphical displaysand can access the Internet (or other communications network) onso-called mini- or micro-browsers, which are web browsers with smallfile sizes that can accommodate the reduced memory constraints of mobilewireless devices. In a representative embodiment, the mobile device is acellular telephone or smart phone that operates over GPRS (GeneralPacket Radio Services), which is a data technology for GSM networks. Inaddition to a conventional voice communication, a given mobile devicecan communicate with another such device via many different types ofmessage transfer techniques, including SMS (short message service),enhanced SMS (EMS), multi-media message (MMS), email WAP, paging, orother known or later-developed wireless data formats.

AC electric cogeneration systems must also contain devices and methodsto direct the flow of electricity within a system. Devices such astransfer switches are known in incorporate logic into their operationthat directs a switch to shift from one power supply to another in theevent that an electrical load is not being met or a malfunction occurs.These switches can be linked to a computer that can evaluate the currentflowing through a switch and how much voltage is necessary to satisfy agiven load demand. Systems are known in the art to switch from one powersupply to another, but as illustrated in the U.S. Pat. No. 7,696,642,these systems are often inefficient, time consuming, or costly.

Thus, in view of the problems and disadvantages associated with priorart devices and methods, the present invention was conceived and one ofits objectives is to provide an electric cogeneration system capable ofmeeting an electrical load with AC power provided simultaneously by asynchronous AC generator and a DC/AC solar inverter powered by a DCsolar array.

It is another objective of the present invention to provide a systemthat can provide AC power back to a utility grid for credit.

It is still another objective of the present invention to provide acontrol system that can monitor and present data regarding an electriccogeneration system, either at a single point or multiple satellitelocations.

It is another objective of the present invention to provide an ACcogeneration system that meets all current and anticipated electricaland fire safety codes and regulations.

It is yet another objective of the present invention to provide anelectric cogeneration system that is based on the flow of alternating(AC) current.

It is a further objective of the present invention to provide a methodfor efficiently distributing AC power from multiple sources such as anAC solar inverter and a synchronous AC Generator.

It is still a further objective of the present invention to provide amethod for isolating the utility provided AC power from the common ACload and the AC generator in compliance with UL 1741 and other safetycodes during the period solar provided AC power and the AC synchronousgenerator are AC coupled by means of an automatic transfer switch (ATS).

It is yet a further objective of the present invention to provide anelectric cogeneration system that is easy to install and inexpensive tooperate while reducing the amount of energy needed from a utilitycompany and the amount of fuel required by the synchronous AC generatorwhile solar AC power is generated and consumed by the common AC load ordirected back to the AC utility grid.

It is a further objective of the present invention to provide a systemwith control logic that can safely under all power and load scenariosbalance the use of solar produced and generator electricity to meet acommon load.

Various other objectives and advantages of the present invention willbecome apparent to those skilled in the art as a more detaileddescription is set forth below.

SUMMARY OF THE INVENTION

The aforesaid and other objectives are realized by providing a powerdistribution system from multiple AC power sources. The system includesa main AC source, a synchronous AC generator, a renewable power sourcesuch as radiant energy captured by a solar panel, and a transfer switch.The main AC source and the AC synchronous generator are connected to thetransfer switch. The system also includes a DC/AC solar inverter, whichis in communication with the solar panel. The transfer switch and theinverter are both connected to an AC common load panel where the ACpower provided by the DC/AC solar inverter, the AC synchronousgenerator, and the main AC source is used to satisfy a common ACelectrical load.

The system further includes a system control device that is incommunication with the inverter and the transfer switch and is capableof selectively determining power input to the common load panel. Thissystem can be built directly into a new building or it may be retrofitonto an existing structure and can also be used with system componentsthat were not previously available for “off grid” application.

The objectives are further realized by providing an AC power couplingand AC power distribution method for efficient distribution of availableAC power sources, the method including the steps of providing an ACpower cogeneration system as described above, measuring AC electricalavailability, type, capacity and AC load requirement with a systemcontrol device, measuring AC power condition and availability atmultiple system points, and selecting the AC power source or combinationof AC power sources to satisfy common AC load requirements. This methodallows for flexible operation of an AC electrical cogeneration systemdepending on the availability of utility power, solar AC poweravailability, synchronous AC generator availability, and common AC loadrequirements, incorporating social and economic advantages as described.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an AC power cogeneration and ACcoupling system;

FIG. 2 is a flow chart showing the AC coupling and cogeneration systemillustrated in FIG. 1 in the presence of, and connected to AC utilitypower;

FIG. 3 is a flow chart showing the operation of the AC power couplingand cogeneration system of FIG. 1 in the absence of AC utility power;

FIG. 3 a is a flow chart showing a continuation of the operational logicof the cogeneration and AC coupling system displayed in FIG. 1;

FIG. 3 b is a flow chart presenting a continuation of the processesillustrated in FIG. 3 a; and

FIG. 4 is a flow chart illustrating the logic sequence of an emergencyshutdown command issued by the system of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT AND OPERATION OF THEINVENTION

For a better understanding of the invention and its operation, turningnow to drawings, FIG. 1 displays all AC power components of cogenerationsystem 10 as shown by single line with bidirectional arrows at eachcomponent connection. All DC power components are shown by a double linewithout arrows between each DC component connection. All signal, analog,digital, cellular, network, or radio communication connections arerepresented by single broken lines between components.

FIG. 1 displays AC electrical cogeneration and AC coupling system 10,which preferably includes solar panel 14, solar controller 34, DC/ACinverter 20, common AC load panel 22, automatic transfer switch 18, loadcontroller 28, synchronous AC generator 12, and generator controller 26.Preferred cogeneration system 10 also includes DC disconnect switch 30and AC disconnect switch 32 which are required by various solarinstallation codes. Utility grid 16 is also included in preferred system10 as an operational baseline which provides a normal AC power conduitfor load panel 22, and for receiving excess solar generated AC powerfrom inverter 20 back through grid 16. Utility grid 16 AC power may beabsent during system 10 operation and is not a requirement for ACcoupling/cogeneration. Charge controller 38 and battery bank 36 areoptional accessories in system 10 to accommodate the controlrequirements of some inverter 20 designs. However charge controller 38and battery bank 36 are not required as a DC to AC power source forsuccessful system 10 operation. Also included in preferred system issystem control device 24 containing programmable logic 40.

Synchronous AC generator 12 shown in FIG. 1 is preferably an ACsynchronous generator with a sine wave alternator commonly manufacturedin single or 3 phase winding configuration, capable of producing voltageand frequencies common to U.S. and International Electrical Codes anddevices. Generator 12 shall be frequency governed by system controldevice 24 and logic 40 to perfect utility match isochronous throughoutload range 0 to 100%. Generator 12 size in terms of Kilowatts (KW) isunlimited, however conventional methodology is to match KW capacity tomeet designated load of common load panel 22 when normal utility grid 16AC power is absent. System 10 will preferably have generator 12 with aminimum of 1 KW.

As is known, an AC synchronous generator such as generator 12 produceselectricity which has voltage, phase rotation and frequency that exactlymatch other system 10 AC power components such as utility grid 16 andsolar inverter 20. During operation, this matching of voltage, phaserotation and frequency may be referred to as synchronous AC parallelingin that two or more components of system 10, for example AC synchronousgenerator 12 and solar panel 14, are servicing load panel 22 withidentical voltage, phase rotation, and frequency of power withoutcausing backfeed in the system which could potentially damage ACsynchronous generator 12. Common methods of operating generator 12include fossil fueled internal combustion engines of appropriate sizefor generator 12 KW output range. Other methods (prime mover) includeswind, hydro-electric, and external combustion. All prime moverapplications employ prime mover electronic governor controls (not shown)that are prime mover speed (frequency) adjusting throughout the ratedgenerator 12 KW ranges. All prime mover applications must be isochronousin frequency from 0 to 100% rated load of generator 12. Generator 12 isrequired to operate at a frequency and voltage range that matches thesensing and operational voltage of inverter 20 under all loadconditions.

FIG. 1 shows solar panel 14 as source of renewable DC energy convertedto AC power at same voltage and isochronous to system 10 through solarinverter 20. Other renewable sources such as wind, hydro-electric, andfuture energy sources may be equally employed as long as this energysource is converted through an inverter such as inverter 20 compatibleto system 10.

Generator controller 26 and load controller 28 are also illustrated inFIG. 1. Generator controller 26 is responsible for starting and stoppingthe prime mover (for example, generator 12 equipped with a fossil fuelinternal combustion engine), monitoring and adjusting parameters ingenerator 12, providing status indicators, alarms, and safety shutdownprotection. Communication and control within generator controller 26 canbe provided by hardware, software, firmware, analog or digital or anycombination of these components as individual applications require.Preferably, system 10 uses common communication languages or MODBUS andCAN, however other languages and methods, may also be employed.Communication may be hard wired, wireless connected via a network (notshown) or any combination thereof. Loss or absence of AC power suppliedby utility grid 16 signals microprocessor 25′ and logic 40 concurrentlyin automatic transfer switch 18, generator controller 26, and systemcontrol device 24.

After a predetermined time out period to ensure that the AC power outagewas not momentary, microprocessor 25′ in automatic transfer switch 18,signals logic 40 in communication with generator controller 26 to startthe prime mover rotating and accelerating to rated isochronous system 10frequency. Voltage regulation sensors (not shown) and generatorcontroller 26 produce voltage rated system 10. Generator controller 26monitors important prime mover functions and operational parameters andimportant generator 12 electrical functions and operational parametersaccording to requirements set forth by IEEE, UL, NFPA, NEC, EGSA, andother AC power regulatory entities. All real time operationalinformation from generator controller 26 and automatic transfer switch18 is sent to control system device 24 via communication methodemployed, normally hardwire RS 485, known as MODBUS.

Once generator 12 is operating with the exact electrical characteristicsof utility grid 16 in terms of voltage, phase rotation, frequency, andphase angle automatic transfer switch 18 initiates a physical electricaldisconnect of utility grid 16 from system 10. Instantaneously, theswitching mechanism in transfer switch 18 connects the generator 12electrically to common load panel 22. This switching process inautomatic transfer switch 18 may be mechanical or static as long as theAC power of utility grid 16 is physically isolated from all AC powercomponents in system 10. At this point the various features of system 10are completely active. For example, see FIG. 2 for a flow chartrepresenting system 10 in its most deactivated state and FIGS. 3-3 b forflow charts presenting system 10 in active stages.

Once AC power transfer at automatic transfer switch 18 has occurred, ACcurrent moves from synchronous AC generator 12 through the now closedcontacts in transfer switch 18 and through the common load panel 22 topower the attached loads (not shown). Solar inverter 20 is electricallyconnected to load panel 22 through the AC power wiring, indicated inFIG. 1 with a single solid line. Microprocessor 25″ and PLC logicslocated inside inverter 20 sense the AC power supplied by the generator12 as electrically identical as that supplied by utility grid 16 andinverter 20 turns on after an optional predetermined time delay. Solarinverter 20 is capable of converting DC electricity from solar panel 12.All solar inverter 20 operational control and data are transmitted tosystem control device 24 via a communication method such as MODBUS.

Simultaneously, AC current flows through accurately calibratedconventional current transformers and other electrical sensors (notshown) located in generator controller 26 and load controller 28.Current transformers and other current measure and control devices likethem in generator controller 26 monitor generator 12 AC current in theoutgoing (to load) direction for control and monitoring purposes. Forexample, one such control purpose is to protect generator 12 fromoverloaded current from excessive AC load in the common load panel 22.An example control response to this occurrence may be to signal a loadto be shed or the main AC generator breaker (not shown) to trip, or toshut the generator 12 down entirely.

The purpose of current transformers and other AC current measure andcontrol devices in load controller 28 is to monitor and control ACcurrent in the incoming direction (towards generator 12). Loadcontroller 28 is a unique feature that protects generator 12 from ACreverse current damage. This reverse current can occur when solarinverter 20 is producing AC current in excess of the AC currentrequirements of common load panel 22 and this current must flow byElectrical Law back into the stator windings (not shown) of generator 12creating damaging inductive currents that destroy sensitive electricaland electronic components. An example of this occurrence is representedin FIG. 4.

All information from generator controller 26 and load controller 28 isrouted to system control device 24 via communication method.Microprocessor 25 and logic 40 within system control device 24 respondto this data with multiple control and data reporting functions (seeFIGS. 2-3 b). In the case of a reverse current signal from loadcontroller 28, for example, system control device 24 responds by sendinga signal to solar controller 34 to turn off solar module(s) (not shown)or entire solar panel 14 until the AC reverse current event ceases. Thereduction or elimination of DC current in solar panel 14 reduces oreliminates the conversion of AC current from inverter 20 to load panel22 which in turn terminates the reverse AC power event.

Synchronous AC generator 12 continues to power the common load panel 22under normal operation when electricity from utility grid 16 is lost.When AC current sensed by load controller 28 rises above a programmedset point, a signal is sent to solar controller 34 by system controldevice 24 to turn solar controller 34 back on in stages or all at oncedepending on user input included with programmed logic 40 and systemalgorithms based on the requirements of a given site contained in systemcontrol device 24.

FIG. 1 further demonstrates DC solar panel 14, consisting of one or moreconventional DC solar modules (not shown) the quantity of which islimited only by designed KW system size. These solar modules may beconnected in electrical series or parallel configurations to form solarDC solar panel 14 as the preferred embodiment of a renewable energycollector serving as a renewable power supply. Tidal generators,bio-digesters, and other generators are all examples of alternativepower sources that could serve the same purpose for electriccogeneration system 10. Although only one DC solar panel 14 is shown fordiscussion, it is understood that electric cogeneration system 10 mayincorporate any number of solar panels 14 arranged to maximize captureof solar generated radiant energy. As is known in the art, solar panel14 is composed of one or more photovoltaic modules, which are comprisedof one or more photovoltaic cells, manufactured for example withstructural substances such as silicon or cadmium telluride andconducting wires composed of copper or silver. Although solar panel 14is illustrated in a fixed position in FIG. 1, mounting methods are knownin the art which allow panel 14 to pivot and track the sun, furtheringincreasing the efficiency of solar panel 14. In one or more alternateembodiments, solar panel 14 may be modified to mount on structuralroofs, adequate ground surfaces, poles and vertical structures, marinevessels, vehicles, trailers in a permanent or portable configuration asindividual system applications require. Solar panel 14 may furtherinclude commercially available solar modulators (not shown) to boost thecollection efficiency and electrical output from panel 14.

Cogeneration system 10 in its preferred embodiment requires solar panel14 to be connected to and controlled by solar controller 34. Solarcontroller 34 may be connected to each solar module, to each modulestring, or directly control the entire solar panel 14 or any combinationor in any connection method not describe here. Solar controller 34 actsas an on/off switch to allow solar generated DC current to flow or ceaseflowing to the DC/AC solar inverter 20 on an individual module level,module string level, or the entire collective solar system panel 14.

Solar 34 is in communication with AC system control device 24 viacommunication method including but not limited in any way to RS 485MODBUS hard wire, wireless communication via cellular, radio wave orother method not described here. Other embodiments may be incorporatedinto the solar controller 34 design including DC to DC shade optimizers,remote monitoring and programming software, hardware and firmware, andother features or improvements known in the art.

Solar panel 14 and solar controller 34 are connected to solar inverter20 through DC solar disconnect 30 and solar AC disconnect 32 as requiredby the National Electric Code (NEC) section 690 and other codes asrequired by AHJ. Solar DC disconnect 30 is a commercially availableswitch that manually or mechanically disconnects or connects the solarDC current supply to the DC side of solar inverter 20. DC solardisconnect 30 is a site required safety and maintenance device toisolate solar derived energy from causing physical injury to equipmentand personnel during maintenance, repair and site emergency situations.

DC/AC solar inverter 20 is shown connected to DC solar disconnect 30 andSolar AC disconnect 32, both manual and mechanical means of isolatingthe DC/AC solar inverted 20 from respective DC and AC voltages for thepurpose life and equipment safety, maintenance and repair of subjectinverter as required by NEC section 690 and other codes. Optionallythese disconnects may be remote operated through wire and wirelesscommunication means operating through AC system control device 24 inFIG. 1. Preferably, DC/AC solar inverter 20 is a synchronous, purelysine wave AC, grid connected and activated. These solar inverter typesare known in the art and commercially available at retail locations.Additional features that may be included in other embodiments of DC/ACsolar inverter 20 include additional capacitors, inductors, and filters(not shown) which can be used to modify wavelength and amplitude of theelectrical signal wave, or pulse-width modulation which is a knownprocedure to modify the AC output current of DC/AC solar inverter 20.Solar inverter 20 may also incorporate remote control and communicationssoftware, firmware, and hardware specifically designed for AC system 10operation as individual applications require.

AC cogeneration and coupling system 10 further supports DC/AC solarinverter 20 designs that include DC mass energy storage, for examplebattery bank 36, in their respective operation. These solar inverters asknown in the industry as “stand alone” or “off grid” are designed tofunction in the absence of any commercial AC power supply from utilitygrid 16. As previously stated, system 10 does not require any DC massstorage to AC couple at any time, except when individual commercialsolar inverters require it to function. Some advantages incorporatedinto this specific design may be uninterrupted power supply (UPS)capabilities to provide continuous and seamless AC power during any ACpower supply transition during system 10 operation.

In DC/AC solar inverter designs that require DC energy mass storage foroperational functionality, solar inverter 20 typically incorporates DCcharge controller 38 and an AC/DC battery charger (not shown) tomaintain the proper DC voltage and current capacity (Amp-hours) forsystem operation and DC battery bank 36 longevity.

Both solar inverter 20 by way of solar inverter AC disconnect 30 andautomatic transfer switch 18 are connected to common AC load panel 22which is preferably a conventional circuit breaker box or panel with amain AC circuit breaker and a plurality of circuit breakers (not shown)as known in the art. The size and features of common AC load panel 22will be unique to the site where it is located, but preferably panel 22will have a combination of different AC current circuit breakers (notshown) designed to trip in the event a fault condition is detected. In aresidential installation, panel 22 may have more low current AC breakerswhile at commercial and industrial sites panel 22 may be composed ofmore medium and high current AC breakers.

Automatic transfer switch 18 is also connected to common AC load panel22, and in the preferred embodiment of electric cogeneration system 10,automatic transfer switch 18 is a “break before make, toggle of linkedlockout contactor automatic transfer switch. An automatic transferswitch such as switch 18 is in continuous communication with AC systemcontrol device 24 and synchronous AC generator controller 26 and has thecapability to communicate the start and operate AC synchronous generator12 and transfer electrical AC load of common AC load panel 22 to ACsynchronous generator 12 once it is meets AC requirements in the eventloss in voltage is detected. This type of switch is commerciallyavailable at retail locations.

Electric cogeneration system 10 is controlled by system control device24, which in the preferred embodiment of cogeneration system 10 is aconventional state of the art programmable logic control, which receivesand processes electrical and system data from key system devices such asDC solar controller 34, DC/AC solar inverter 20, common AC load panel22, automatic transfer switch 18, synchronous AC generator loadcontroller 28, and synchronous AC generator controller 12. Othermonitoring and data collecting points may be added per site specificapplication as desired. System control device 24 controls the access andcurrent flow of all AC power sources to achieve AC coupling, AC powercontrol and direction, and design features utilizing hardware, software,firmware, languages, and digital and analog communications available inthe industry and to be developed for application. System control device24 is configured for local and remote programming throughout the rangeof system sizes (KW) and application site diversity. System controldevice 24 houses system logic 40 which in turn governs communicationhardware, software, and firmware, associated communication languages,and equipment, to ensure that system 10 complies with current industrystandards for safety and efficiency.

System logic 40 conveys visual, analog, and digital informationconcerning the condition and operation of individual system componentsas well as complete system 10 status and operations in a local as wellas remote capacity. System logic 40 interfaces with devices such ascomputers, fixed and portable, internet devices, modems, hard wiredcircuits, cellular, and satellite communications devices andmethodologies, visual display screens, auditory alarms and other methodsnot stated here. Some remote programming and system 10 control functionsare incorporated into system 40 output and function.

FIGS. 2-4 present flow charts illustrating the operation of AC utilitygrid 16, AC automatic transfer switch 18, synchronous AC generator 12,generator controller 26, DC/AC solar inverter 20, DC solar panel 14,solar controller 34, common AC load panel 22, AC system control device24, and system logic 40 in various operating environments of ACcogeneration and AC coupling system 10.

A method of operating AC electrical cogeneration and AC coupling system10 illustrated in FIG. 1 is shown in FIG. 2 in the presence ofelectricity from AC utility grid 16. Preferred method 50 includes step52 measuring AC power, voltage, phase rotation, frequency, and amperagefor load utility, generator and solar. Preferred method 50 also includesstep 54 communicating with automatic transfer switch 18 to determineutility grid 16 AC power is consistent with predetermined specificationscalculated by system control device 24. Preferred method 50 furtherincludes step 56 system control device 24 querying DC/AC solar inverter20 to determine if AC solar power is available, and if so, ascertainingthe availability, amount, and characteristics of the available solarpower as generated by DC solar panel 14, monitored and transmittedthrough closed circuit electronic switches of DC solar controller 34,passed the closed switching contacts of DC solar disconnect 30, invertedto AC current by DC/AC solar inverter 20 and supplied to common AC panel22 through closed switchable contacts in the solar inverter ACdisconnect 32.

In the event step 56 determines that AC solar power is not available,step 57 satisfies the load requirement with electricity from utilitygrid 16 through the closed electro-mechanical contacts within automatictransfer switch 18. However, in the event step 56 determines that ACsolar power is available from DC/AC solar inverter 20, preferred method50 additionally includes step 60 system control device 24 evaluating ifthe available AC current exceeds the present load requirement. If ACsolar current is determined to exceed the current requirements in step60, step 70 system control device 24 directs the excess solar AC currentfrom solar inverter 20 through the closed breakers (not shown) of commonload panel 22, through the closed, switchable electro-mechanicalcontacts in automatic transfer switch 18 back to AC utility grid 16.Method 50 may also include step 72 sending the surplus electricitythrough a power metering device (not shown) to become absorbed by the ACutility transmission system of utility grid 16.

If system control device 24 determines in step 70 not to export excessAC solar current, for example due to some unexpected system condition,preferred method 50 further includes step 74 “throttling” (i.e.increasing or decreasing to match system conditions as dictated bysystem control device 24) AC solar current to an AC current level thatmeets system conditions and parameters. Specifically, this AC solar“throttling” is achieved through commands issued to various controlmechanisms, for example DC/AC solar inverter 20, DC solar controller 34or both. If system control device 24 determines there is not sufficientAC solar current in excess of common load panel 22 requirement, step 62all available AC solar current from solar inverter 20 is supplementedwith AC current from the utility grid 16 through the devices andcontrols previously described.

FIG. 3 depicts the operation of cogeneration and AC coupling system 10in the absence of utility grid 16 electricity. Automatic transfer switch18 senses the loss AC utility power from utility grid 16 step 54 andcommands the synchronous AC generator to start (the preferred example ofa fossil fueled internal combustion prime mover) and accelerate to aconstant rotational speed that matches the required AC system frequency(also known as an isochronous frequency). Required AC voltage isproduced in the proper phase sequence and sine wave characteristic ofgenerator 12. Automatic transfer switch 18 receives acceptableparameters from system control device 24 and opens the switchableelectro-mechanical contacts located within automatic transfer switch 18disrupting the AC power connection between utility grid 16 and commonload panel 22 and closes the AC power contact between synchronousgenerator 12 and common load panel 22. Utility grid 16 is electricallyisolated from the solar inverter 20 in the absence of utility AC poweras required by UL 1741 and other codes. Synchronous AC generator 12 step66 provides all the AC power required by the common load panel 22.

Solar inverter 20 receives the AC voltage and frequency from synchronousAC generator 12 through a closed breaker in common load panel 22 whichcauses solar inverter 20 to furnish DC power supplied from DC Solarpanel 14 as previously described in FIG. 2. Inverter 20 is capable ofproviding AC solar power commensurate with the degree of DC solar energyavailable. Preferred method 50 further includes step 76 system controldevice 24 receiving system data that all electricity parameters andconditions are met and allowing solar inverter 20 to AC couple withgenerator 12 AC output. Preferred method 50 also includes step 78 systemcontrol device 24 commanding solar inverter 20 and solar controller 34to operate and provide AC solar power to common load panel 22.

Preferred method 50 of operating AC cogeneration and AC coupling system10 continues in FIG. 3 a. Method 50 further includes step 64 generator12 and solar panel 14 servicing the load while system control device 24is monitoring electricity load requirements and all contributing ACsources while power is unavailable from utility grid 16 (see step 66 inFIG. 3). During step 64, system control device 24 is activelycontrolling system 10, furnishing AC solar power via solar inverter 20and AC generator power from generator 12 in an AC coupled manner tocommon load panel 22. Preferred method 50 still further includes step 75system control device 24 continuously monitoring the availability ofutility grid 16. If utility grid 16 becomes available, method 50 alsoincludes step 71 automatic transfer switch 18 sensing the availabilityand quality of power from utility grid 16 and timing out programmedtransfer delays. Automatic transfer switch 18 also transfers the load ofcommon load panel 22 back to utility grid 16 and electro-mechanicallylocks out synchronous AC generator 12 from common load panel 22.Further, a stop generator command is sent to generator controller 26 andsolar inverter 20 is deactivated, stopping the AC solar current. Afterthese functions are performed, system 10 returns to the state depictedin FIG. 2. In the alternative, if utility grid 16 remains unavailable,method 50 includes step 78 system control device 24 commanding solarinverter 20 and solar controller 34 to continue operating (see FIG. 3b).

FIG. 3 b is a flow chart showing a continuation of operational logic 40of cogeneration and AC coupling system 10 displayed in FIG. 1. Method 50repeats steps, 52 and 64 as previously described, further including step73, system control device 24 determining if system parameters based onthe location housing system 10 are met to add or shed AC solar currentcapacity.

If system parameters are not met, method 50 mandates a return loop tostep 64. However, if system parameters are satisfied, method 50preferably further includes step 79 system control device 24 controllingsolar controller 34 and/or solar inverter 20 to add or shed AC solarcurrent by restricting the flow of current to common load panel 22.Preferred method 50 still further includes step 75 system control device24 monitoring for availability of AC utility grid 16. If utility grid 16becomes available method 50 returns to step 71 (FIG. 3 a), but if ACpower from utility grid 16 is not available, method 50 returns to step64.

FIG. 4 is a flow chart showing the logic sequence of an emergencyshutdown command issued by system 10. Method 50 repeats steps 52 and 64as previously described, and preferably includes step 80 system controldevice 24 deciding whether an emergency shutdown is required. Anemergency shutdown may be a manual or automatic control functionresulting from a system or site catastrophic event that could causehuman, hardware, software, or firmware damage if system 10 is leftactive. Examples would include fire in the vicinity of the solar panel14, or loss of major sensor inputs for system control device 24, orfailure of system control device 24 itself. If step 80 is not required,method 50 returns to step 64. If step 80 is necessary, integratedfailsafe circuits in system control device 24 command synchronousgenerator 12, solar controller 34, solar panel 14, and solar inverter 20to shut down, disperse all power and lock out these power sources, untilstep 82 requiring a manual reset of system 10. Method 50 furtherincludes step 84 continuing to lock out generator 12 and solar panel 12and step 75 automatic transfer switch 18 sensing available AC power fromutility grid 16 AC. If utility grid 16 is available, method 50 includesstep 86 transfer switch 18 transferring common load panel 22 back toutility grid 16 AC power; however system 10 components in step 82 remainlocked out until manual system reset.

We claim:
 1. A method of synchronously paralleling multiple AC power sources, the method comprising the steps of: a) providing a paralleling system comprising a main AC power source, a synchronous AC generator, a solar panel, a solar controller, said solar panel linked to said solar controller, a DC disconnect, said solar controller connected to said DC disconnect, an AC disconnect, a transfer switch, a generator controller, a load controller, said generator and load controllers connected to said synchronous AC generator, said main AC power source and said load controller connected to said transfer switch, an inverter, said inverter in communication with said AC disconnect, a load panel, said transfer switch and said inverter connected to said load panel, a system control device, said system control device in communication with said inverter, said transfer switch, said solar controller, said generator controller, and said load controller; b) measuring an electrical load by said system control device at said load panel; c) selecting an AC power source to satisfy the electrical load; d) configuring the system control device to match AC power produced by the synchronous AC generator and the renewable power source to power produced by the main AC power source; e) detecting a reverse power flow event at the AC synchronous generator; and f) throttling power produced by the renewable power source to decrease available AC power until the reverse power flow event ceases.
 2. The method of claim 1 further comprising the step of determining, via the system control device, the availability of electricity from the main AC power source.
 3. The method of claim 2 wherein the step of managing AC power output further comprises returning electricity in excess of the electrical load provided by the solar panel to the main AC power source.
 4. The method of claim 3 further including the step of changing the source of AC power from the main AC power source to the synchronous AC generator via the automatic transfer switch.
 5. The method of claim 4 wherein the step of changing the source of AC power further comprises the step of starting the synchronous AC generator.
 6. The method of claim 2 wherein the system control device delays a predetermined time to determine the availability of electricity from the main AC power source.
 7. The method of claim 1 further comprising the step of reducing the amount of electricity produced by the synchronous AC generator by the amount of electricity provided by the solar panel.
 8. The method of claim 7 further comprising the step of switching the AC power source to the main AC power source via the transfer switch should the electrical load requirement not be met and the main AC power source be available.
 9. An electrical cogeneration system for synchronously AC paralleling multiple AC power sources, said system comprising a synchronous AC generator, a renewable power source, a system control device, said system control device in communication with said synchronous AC generator and said renewable power source, said system control device configured to match AC power produced by said synchronous AC generator and said renewable power source, whereby said system control device detects the presence of a reverse power flow event proximate said synchronous AC generator and throttles power produced by said renewable power source to decrease available AC power until said reverse power flow event ceases.
 10. The system of claim 9 further comprising an automatic transfer switch connected to a main AC power source, an inverter, and a load panel, said system control device in communication with said transfer switch, said inverter, and said load panel, said main AC power source and said synchronous AC generator connected to said transfer switch, said renewable power source connected to said inverter, said transfer switch and said inverter connected to said load panel, said system control device in communication with said transfer switch and said inverter.
 11. The system of claim 9 further comprising a generator controller, a load controller, said generator controller attached to said synchronous AC generator and in communication with said system control device, said load controller connected to said synchronous AC generator, said load controller in communication with said system control device and said transfer switch.
 12. The system of claim 11 further comprising a DC disconnect, an AC disconnect, said DC disconnect connected to said solar panel and said inverter, said AC disconnect connected to said inverter and said load panel.
 13. The system of claim 12 further comprising a solar controller, said solar controller connected to said solar panel and said DC disconnect, said solar controller in communication with said system control device.
 14. The system of claim 13 further comprising a battery, a charge controller, said charge controller connected to said battery and in communication with said inverter.
 15. The system of claim 9 wherein said system control device includes programmable logic.
 16. The system of claim 15 wherein said programmable logic is configured to reduce synchronous AC generator power output should said output exceed demand.
 17. The system of claim 15 wherein said programmable logic is configured to reduce renewable power source power output should said output exceed demand.
 18. The system of claim 15 wherein said programmable logic is configured to export power produced by said renewable power source should output of said renewable power source power exceed demand.
 19. A method for synchronously AC paralleling multiple AC power sources, the method comprising the steps of: a) providing a paralleling system comprising a main AC power source, a synchronous AC generator, and a renewable power source in communication via a system control device; b) configuring the system control device to match AC power produced by the synchronous AC generator and the renewable power source to the main AC power source; c) detecting a reverse power flow event at the AC synchronous generator; and d) throttling power produced by the renewable power source to decrease available AC power until the reverse power flow event ceases.
 20. The method of claim 19 further comprising the step of determining the availability or absence of power from the main AC power source via the system control device. 